It is important to be able to measure electric current accurately. Applications for which accurate current measurement is important include:                by utility companies delivering electric energy to customers;        for control of industrial processes, such as electroplating and electrolytic manufacture of copper and other metals;        for proper functioning of alternative-energy generators, such as wind and photovoltaic; and        for estimation of state of charge in batteries for off-grid storage, electric vehicles, cell phones, portable computers, and in myriad other electrically powered devices.        
Most of these applications require precise knowledge of the current over a wide dynamic range. In a current measurement device that works over a wide dynamic range, it is not easy to find a way to keep the measurement errors small at times when the current is near zero.
Of the several direct and indirect techniques that exist for measurements of current, the two most popular are the voltage drop sensing on a resistor due to Ohm's law (such a resistor is often called shunt, current shunt, or resistive shunt), and devices based on sensing of the magnetic field generated by the current. Each of these approaches for current measurement has advantages and disadvantages. Devices based on magnetic field detection are vulnerable to any nearby magnetic fields as well as to the magnetic field of the Earth. Current measurement by means of a resistive shunt is, by comparison, simple, robust, and as a rule less expensive, but a resistive shunt is prone to thermoelectric errors due to the so-called Seebeck effect, a physical phenomenon that results in generation of error voltages in the measurement circuit when a part of the circuit has a different temperature than another part of the circuit. Any shunt by definition has non-zero resistance and thus when current is flowing it heats up due to so-called ohmic losses. The ohmic losses, together with other possible nearby heat sources or sinks, give rise to temperature differentials that in turn cause thermoelectric errors.
For generation of thermoelectric errors, it is not enough that a part of the circuit has a different temperature than another part of the circuit. There must in addition be dissimilar materials in various parts of the circuit. In a current measurement device employing a resistive shunt, a typical source of dissimilar materials is the choice of materials for the shunt itself and for its sensing leads.
For example, in the commonly-used prior-art approach shown in FIG. 1a, the sensing lead wire 13 for the shunt is attached using bolt 15 and nut 17, as well as lock washers 16, and o-ring crimp terminal 14 that is connected to the sense lead 13 by the crimp (compression) operation on the terminal 14. Such a scheme juxtaposes many non-identical materials in series and parallel relationships relative to the signal path. This gives rise to a variety of thermoelectric voltages when the shunt heats up.
A prior-art arrangement in FIG. 1b depicts the attachment of a lead 11 using soldering, brazing, or welding. One problem with soldering or brazing (and with some kinds of welding) is that the solder or filler material 12 will present a non-identical material and thus will present an opportunity for thermoelectric voltages. While the amount of solder or filler material 12 between and thereabout the lead 11 and the conductive structure 10 can be reduced, it cannot be eliminated completely.
A further drawback to the use of soldering, brazing, or welding to attach a lead may be seen when one appreciates that the shunt will have been carefully processed prior to the attachment activity, and will likely have been thermally treated or annealed prior to the attachment activity. The application of significant heat (for the soldering, brazing, or welding activity) risks upsetting characteristics of the shunt that were the object of the thermal treatment or annealing. For example there may be a degradation of the thermal stability of the resistivity of the shunt in the areas affected by the heating activity.
Both of these prior-art arrangements also suffer from a rigid attachment of a lead to a shunt. In FIG. 1a the wire 13 is rigidly attached to the terminal 14 (at the crimp point). In FIG. 1b the lead 11 is rigidly attached to the structure 10. A rigid attachment creates a place where mechanical stresses are concentrated, leading to a possible rupture of the wire or lead at the point of rigid attachment. It is possible to apply an external stress-relief component, either in the form of flexible tubing or a specifically engineered part, however this is cumbersome and incurs some cost.